Electric plug having a conductor operated ejector



Dec 7, 1954 P. HARRINGTON Erm. 2,696,594

ELECTRIC PLUG HAVING A CONDUCTOR OPERATED EJECTOR PETE' HARR/NGTON I BURT W THOMPSON,

. I N VEN TORS.

A T TORNEV.

Dec. 7, 1954 P HARRINGTON ErAL 2,696,594

ELECTRIC PLUG HAVING A CONDUCTOR OPERATED EJECTOR L N 4 6 f@ i 7 59 60' i 37 if j Il PETE' HARR/NG' ON EUR T W. THOMPSON, IN VEN TORS.

A TTORNE K United States Patent Oice 2,696,594 Patented Dec. 7, 1954 ELECTRIC PLUG HAVING A CQNDUCTOR OPERATED EJECTOR Pete Harrington, Burbank, and Burt W. Thompson, Los Angeles, Calif.

Application August 27, 1953, Serial No. 376,790

5 Claims. (Cl. 339-45) The invention relates to an electric plug having a conductor operated ejector.

ln the ordinary case, pulling on the electric cord in order to remove the plug from its socket or wall receptacle is apt to be injurious to the cord or loosen the terminals where the conductors are connected to the plug. This is not so in the present invention, as the plug is specially constructed to provide for relative movement between the conductor terminal and the plug so as to translate a pull on the cord into the operation of an ejector device which urges the plug away from its socket. This overcomes the inconvenience of manually engaging the plug to pull it out from its socket and similarly overcomes the inconvenience of manually operating a plug lifter on the plug as heretofore proposed.

An obiect of the invention therefor is to convert a pull on the cord into a force which urges the plug ont of its socket.

A further object of the invention is to urge the plug awav from its socket with a greater force than the force of the pull applied to the conductor. This is accomplished by providing an ejector device operated by a lever system having` a mechanical advantage greater than unity.

Further objects of the invention are t provide an electric plug which is sturdy in construction and wherein the proper electrical connection is maintained during relative movement of the parts in a manner to meet the underwriters requirements.

For further details of the invention reference may be made to the drawings wherein:

Fig. 1 is a vertical sectional view on line 1 1 of Fig. 4, the latter showing a bottom plan View, of an electric plug according to the present invention.

2 is a vertical sectional view on line 2 2 of 1g. 1: Fi. 3 is a horizontal sectional view on line 3 3 of Fig. 5 is a sectional view corresponding to Fig. l, Fig. l showing the ejector pins in extended position while Fig. 5 shows them in retracted position.

Fig. 6 is a sectional view on line 6 6 of Fig. 5.

The above sectional views are looking in the directions of the respective arrows.

Fig. 7 is a horizontal sectional View with parts broken awaV showing one of the brackets.

Fig. 8 is an exploded perspective View with certain parts removed.

Referring in detail to the drawings, the electric plug 1 comprises a casing 2 of insulating material. Casing 2 has a cylindrical neck 3 which merges with an enlarged elliptical wall 4 providing a chamber 5. The chamber 5 is removably closed by an end plate 6 held by screws like 7 having thread engagement with nuts 8.

The neck 3 has a cylindrical bore 9 in which slides a terminal block 10 of insulating material. The block 10 at its outer end has a recess 11 for a split ring 12 locked by screws like 13, three being shown, which have thread engagement with nuts like 14, to clamp the cable 15 as slown at 16. The cable 15 has two conductors 17 and 1 The block 10 slides in the bore 9 and its outward movement is limited as the outer end of the neck 3 is constricted as shown at 19 to provide an abutment for the outer end of the block 10.

Inwardly of the recess 11, the block 10 has a tortuous passage 20 for the conductors 17 and 18, to resist the plug is inserted in the socket.

cable from pulling out from the block 10. The lower end of block 10 as shown in Fig. 2 has an extension 21 having opposite flat sides against which the terminal plates 22 and 23 lit, each plate having an inturned lower end as shown at 24 to receive a screw like 2S which holds the lower end of plate 22 in position, its upper end being held to the extension 21 by a screw like 26 which also serves to clamp the end of the conductor like 17 to the top of the plate like 22. The upper screw for the other conductor 18 is shown at 27 in Fig. 2, and the lower `screw is shown at 28 in Fig. 5.

Screw 25 also passes through an aperture in and clamps the inner end 29 of a leaf spring 30, the spring end 29 being arranged between the end 24 of the plate 22 and the lower end of extension 21. Screw 28 similarly clamps and holds the 'inner end 31 of a leaf spring 32.

The end plate 6 has two spaced contact pins or prongs 33 and 34, to t the usual electrical socket. The pins 33 and 34 each has upset portions as indicated at 35 to anchor the same in the insulating end plate 6 when moulded therein. Each contact pin like 33 has a lateral extension like 36. see also Fig. 8, and an inturned portion 37 anchored in the end plate 6. The lateral portion 36 has a bore or bearing aperture 38 for an ejector pin 39. The lateral portion 36 also has an upright extension 40 having an offset arm 41 having an aperture 42 for a pin 43 on which fit the aperture 44 of a brush 45 and the aperture 46 in a lever arm 47 which may be of insulating material. Plate 23 slides on brush 45.

The other contact pin 33 similarly has a brush 48 for the terminal plate 22. As the terminal block 1G slides back and forth in the bore 9, conductor 17 being connected to plate 22 is maintained in electrical connection with contact pin 33 through the brush 48 on plate 22. The other conductor 18 is similarly maintained in electrical connection with contact pin 34 through brush 45 and plate 23.

Extension 66 of contact pin 33 has a pivot pin 49 for brush 48 and for a lever arm 50 which are held on pin 49 by a tension washer 51 and lock ring 52. Lever 47 and brush 45 are similarly held on pin 43 by a tension washer 53 and lock ring 54.

It was mentioned above that ejector pin 39 slides in a bore 38 in the contact pin extension 36. Bore 38 lines up with a similar bore 55 in the end plate 6 so that in fact the ejector pin 39 slides in the bores 38 and 55. The inner end of ejector pin 39 has an enlarged head 56 to limit its outward movement. The contact pin 34 and its extensions 36 and 40 may be struck up from one piece of metal and constitute what may be termed a bracket. The contact pin 33 is a similar bracket reversed in position and it has a similar ejector pin 57 which is similarly supported for sliding movement in the bore 58 in the end plate 6 and in the aligned bore 59 of the lateral extension 60, see Fig. 7, of the bracket of which the contact pin 33 forms a part.

The spring 30 at its outer end has a hinge connection 61 with one end of lever 50 and the other end of lever 50 has a roller 62 which bears on and operates the inner end of ejector pin 39. Similarly, the outer end of spring 32 has a hinge connection 63 with one end of lever 47 and the other end of lever 47 has a roller 64 which bears on the head of ejector pin 57.

The springs 30 and 32 extend into chamber 5 and are curved as shown as the inner end of each spring moves at diterent distances from the end of its responsive lever as the terminal block 1i) slides in and out.

Assuming the terminal block is outermost in the neck 3, with ejector pins 39 and 57 extending outwardly from the end plate 6 as shown in Fig. l, on inserting the plug 1 in a conventional socket, the pins 39 and 57 bear against the front plate of the socket, indicated at 65 in Fig. 5, so that the ejector pins 39 and 57 are pushed in as the Inward movement of the pins 39 and 57, acting through their levers 50 and 47, respectively, draws the terminal block 10 into the neck 3. This operation can be assisted or accomplished by shoving in on the cable 15 if so desired. When it is desired to withdraw the plug 1 from its socket, a pull on the cable 15 slides the terminal block 10 outwardly of neck 3 in one direction so that the springs 30 and 32 operate the leve'rs A47 andiSi) "to push out the ejector pins Fl-and -395 respectively,-intheoppositedirectiong vto `force or eject the plug 1 out of its socket.

Preferably each lever 47-and 50 gives a mechanical advantage; bynreasonoLtheiact that the l:leve1'arrn from thepivot pointsuch as:pirrl 43.--toi-ts.. roller 64 is shorter than the lever larm from the pin.43 to its fspring hinge connectionl, whereby -the.forceacting,orrthe ejectorpins is increased by'lthe .ratio-of Vthese lever? arms.-

- All gures Lin.the.drawings..areenlargedfas itfis-:contemplated lthat inwits preferred-`form,=fthis plug Aisv'of sub.- sta'ntially the. samensize. `asl'a conventional clectricplug employed for household appliances suchtas vacuum cleaners, flat irons; etc.n The constmct-ionisone whrich a pull on thercahle does noharmto the elect-ricalkcmnnection and .in fact .such force [of .pullis multipliedV andfcaused to.ejecta.the plug.

`Those parts required. torestablish.; through.Y connection from azconductor :to its4 comacbpirry are of .meta-l such as copper: or. thelike and themema'iningelements-.may be Yof either. insulating.` material ,.or. .of .metal properly insulated as f well funderstood.V

Manufacture: of. the.1device'.. issimplied as@ the Ytwo levers are .exactly alike,.the. two slidingplatesare exactly alike, the. brushes =are..duplicates.. andv the contact pin bracketsare duplicates, thememberso'feach set-being reversed in zpositiorras shown -in .Eig.`.`8. Thus it would only be necessary to .manufacture aplurality vof^one of each of 'these items.

vThe parts may be readily assembled or repaired by removing end plate 6 which is accomplished by unscrewing the two screws like 7.

Various modifications may be made in the invention without departing lfrom the spirit of the .following claims.

We claim:

1. An electric .plug comprising a casing, a=. terminal block slidable in saidcasing, said block having a-.pair ofrcontact plates and a screw for connecting acordtereach of said pins and one of said plates and an ejector device operated by said terminal block.

2. An electric plug having a sliding terminal block, means for securing in said block a cable having conductors, said'block having conductor plates and means for connecting each of said conductors to one of said plates, contact'pins and' means for maintaining Iconnection between each'ofi said pins androne of said plates, and an ejector device comprisingejecting pins and a mechanical movement operatively connecting said ejecting pins and said terminalblck'for urging said pins outwardly. in. one vdirection-whensaid cable yis pulled to move saidv terminal block'in the opposite direction.

3. An electricfplug vaccording to clai1n2, said plug having an inner end plate having bearing apertures supporting said ejecting pins respectively for movement substantially -parallel .to said-,contact Vpins: and in-.positrionf-for retraction of said ejecting pins byfcontaet'withthe .face plate of a socketon .insertion .ofi-the plugin the.1socket.

4..An electricplug comprising a. casing .hav-inganend plate, .said end :plate .having .acontact .pin-and .a bearing aperture, anejector pin. slidablein..said aperturevlengt-hwiseof saidcontact pin, alever having opposite.:arms, a pivotal supportinsaid. casing for said lever, .an'operative connectionbetween one..of. said leverarms and .said ejector pin, a conductor. terminal .device slidable` insaid casing, means mechanically connectingfsaidterminal device and the other end of .said lever. arm and .meansmaintaining electrical connectionbetween .said terminaldevice nd said contact pin during.movement..of.said.terminal evlce.

5. An electric plug accordingto claim 4, `said vlever arm for said ejector pinzbeing shorter in length=than said other lever arm.

No referencescit'ed. 

